Backflow preventers prevent backflow of toxic contaminants or pollutants into a potable water supply. Backflow preventers are used on potable water lines where a health hazard could exist if a backflow or back siphonage of contaminated water were to occur. If after passing through the backflow preventer the water becomes or may become contaminated, a backflow preventer prevents the water from backing up or returning to, and thus contaminating, the potable water supply. Backflow preventer devices are often required when the same water supply is used for both public usage (i.e. tap water, bathing water, etc.) and for fire protection systems (i.e. sprinkler systems). Backflow preventers are also used when a separate water supply is provided for public usage and fire protection systems, in either or both of the separate water lines which feed the public usage and the fire protection system.
A backflow preventer device generally consists of at least a double check valve assembly, two shut-off valves, and a plurality of test cocks. The shut off valves are positioned on the upstream and down stream sides of the double check valve assembly. With respect to backflow preventers which are installed in the water supply line for the fire protection system, there exists a need to insure that unauthorized persons do not tamper with the shut-off valves, that authorized persons, such as plumbers, who have closed the shut off valves to work on the fire protection system do not forget to turn the shut-off valves to the open position after the work is complete.
At present, a chain and a padlock are often used to lock the shut-off valve handles of the backflow preventer in an open position to prevent unauthorized movement of the valve handles. However, this method of preventing unauthorized persons from accessing the valve handles does not provide for remotely monitoring whether the position of the valve handles may be changed.
In the case where a common water supply is used for both public usage and fire protection systems, it will generally be known when the water supply has been shut-off, since public users will be alerted to the shut off when they attempt to access the water. In this case, the present invention is useful in assisting the prevention of vandals or unauthorized persons from shutting off the water supply at the backflow preventer device when the public users are not in the building or when the public users are not ordinarily using water, such as between the hours of 12:00 AM and 5:00 AM.
The present invention is primarily directed to the case where separate water supply lines supply water for public usage and fire protection systems. In this case, it is possible that an authorized person (e.g. a plumber) who has turned the water off to work on the line may inadvertently forget to turn the water back on, which condition may not be noticed until water is required to prevent or put out a fire. If the water is not available at that time, the results could be disastrous. The present invention also detects whether unauthorized persons or vandals could shut off the fire protection system water, so that the shut-off valves can be checked and, if necessary, placed in the open position, hopefully prior to an emergency situation occurring. Further, the present invention is capable of working under adverse conditions and in wet environments.
The present invention provides a tamper bar which discourages tampering with a backflow preventer valve and monitors the condition of the tamper bar with a switch. The switch provides a signal which can be remotely monitored, for instance, at a central station. In some areas this will allow a common water supply for a fire protection system and a potable water system.